This invention relates to a procedure for estimating the torque transmitted by a friction clutch.
More specifically, the subject of the invention is a procedure for estimating the torque transmitted by a friction clutch coupled to a motor-vehicle engine shaft and controlled by an actuator.
The information in a motor vehicle regarding the magnitude of the torque transmitted by such a friction clutch is useful for a multiplicity of purposes, for example for correcting or updating a “transmissibility map” of the actuator associated with the clutch in a motor vehicle equipped with a gearbox of the “robotized” type. The transmissibility map of the actuator essentially makes every value of an actuator control variable (for example the intensity of the excitation current) correspond with a corresponding predetermined value of the torque transmitted by the clutch.
In a motor vehicle equipped with a gearbox of the robotized type, the actuator associated with the friction clutch is controlled by algorithms which manage the starting or pickup stage as well as the shifting stages, optimizing the performance of the motor vehicle and/or driving comfort, depending on the user's preferences. These algorithms typically use the transmissibility map of the complex formed by the clutch and by the associated actuator. Moreover, the characteristics of the actuator and of the clutch may change over time, even considerably, following wear and as an effect of the working conditions.
In order to guarantee the maintenance of the performance and/or driving comfort, it is necessary for the control algorithms to be enabled to correct or update the characteristics of the clutch/actuator complex in the course of its working life. For this purpose it is necessary to be able to precisely and rapidly estimate the torque transmitted by the friction clutch in what are known as the torque modulation stages, i.e. starting from the information available on board the motor vehicle, in order then to be able to correct the transmissibility map on the basis of this estimate.
One object of the present invention is therefore to make available a procedure which makes it possible to obtain an estimate of the torque transmitted by a friction clutch with good precision, high estimating speed, and robustness vis-à-vis the uncertainties about the data used, and a good level of rejection of the disturbances and noise which typically afflict the magnitudes measured.